Summary of findings 2. Summary of findings: oxcarbazepine versus phenytoin (secondary outcomes).
| Oxcarbazepine compared with phenytoin for epilepsy | ||||||
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Patient or population: adults and children with newly diagnosed epilepsy Settings: outpatients Intervention: oxcarbazepine Comparison: phenytoin | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of Participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Phenytoin | Oxcarbazepine | |||||
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Time to first seizure (post‐randomisation) All participants Range of follow‐up: 1 to 779 days |
The median time to first seizure was 230 days in the phenytoin group | The median time to first seizure was 252 days (22 days longer) in the oxcarbazepine group |
HR 0.97 (0.75 to 1.26)a |
468 (2 trials) | ⊕⊕⊕⊝ moderateb | HR < 1 indicates a clinical advantage for oxcarbazepine |
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Time to first seizure (post‐randomisation) Subgroup: focal onset seizures Range of follow‐up: 1 to 498 days |
The median time to treatment first seizure was 224 days in the phenytoin group | The median time to first seizure was 233 days (9 days longer) in the oxcarbazepine group |
HR 0.92 (0.68 to 1.25) |
326 (2 trials) | ⊕⊕⊕⊝ moderateb | HR < 1 indicates a clinical advantage for oxcarbazepine |
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Time to first seizure (post‐randomisation) Subgroup: generalised onset seizures Range of follow‐up: 1 to 779 days |
The 25th percentile** of time to first seizure was 78 days in the phenytoin group | The 25th percentile** of time to first seizure was 28 days (50 days shorter) in the oxcarbazepine group |
HR 1.11 (0.66 to 1.86) |
142 (2 trials) | ⊕⊕⊝⊝ lowb,c | HR < 1 indicates a clinical advantage for oxcarbazepine |
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Time to achieve 12‐month remission (seizure‐free period) All participants Range of follow‐up: 1 to 532 days |
The median time to 12‐month remission was 401 days in the phenytoin group | The median time to 12‐month remission was 365 days (36 days shorter) in the oxcarbazepine group |
HR 1.04 (0.77 to 1.41)a |
468 (2 trials) | ⊕⊕⊕⊝ moderateb | HR < 1 indicates a clinical advantage for phenytoin |
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Time to achieve 12‐month remission (seizure‐free period) Subgroup: focal onset seizures Range of follow‐up: 1 to 532 days |
The median time to 12‐month remission was 401 days in the phenytoin group | The median time to 12‐month remission was 390 days (11 days shorter) in the oxcarbazepine group |
HR 1.09 (0.75 to 1.57) |
326 (2 trials) | ⊕⊕⊕⊝ moderateb | HR < 1 indicates a clinical advantage for phenytoin |
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Time to achieve 12‐month remission (seizure‐free period) Subgroup: generalised onset seizures Range of follow‐up: 1 to 532 days |
The median time to 12‐month remission was 365 days in the phenytoin group | The median time to 12‐month remission was 365 days (0 days shorter or longer) in the oxcarbazepine group |
HR 0.94 (0.55 to 1.62) |
142 (2 trials) | ⊕⊕⊝⊝ lowb,c | HR < 1 indicates a clinical advantage for phenytoin |
| * Illustrative risks in the oxcarbazepine and phenytoin groups are calculated at the median time to first seizure or time to 12‐month remission (i.e. the time to 50% of participants experiencing a first seizure or 12‐months of remission) within each group across all trials. The relative effect (pooled hazard ratio) shows the comparison of 'time to first seizure' or 'time to 12‐month remission' between the treatment groups. ** The 25th percentile of time to first seizure (i.e. the time to 25% of participants experiencing a first seizure) is presented for the subgroup with generalised seizures as less than 50% of participants experienced a seizure recurrence in both groups, therefore the median time could not be calculated. Abbreviations: 95% CI: 95% confidence interval; HR: hazard ratio | ||||||
| GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||||
a. Pooled hazard ratio for all participants adjusted for epilepsy type.
b. Downgraded once due to risk of bias: as participants who failed treatment or withdrew from the treatment were no longer followed up in the study, remission and seizure outcomes had to be censored at time of treatment failure, therefore remission and seizure outcomes could not be analysed with an intention‐to‐treat approach.
c. Downgraded once due to risk of bias: up to 29% of adult participants classified as experiencing generalised onset seizures (in Bill 1997) may have had their epilepsy type wrongly classified, and sensitivity analyses show that misclassification may have had an impact on the conclusions drawn for individuals with generalised seizures and whether an interaction between treatment effect and epilepsy type exists.